Teacher Turnover Negatively Impacts Student Achievement in Math and English

Teacher turnover results in lower student scores in math and English language arts, according to a researcher from the University of Michigan School of Education and two colleagues.

Matthew Ronfeldt, assistant professor of educational studies at the University of Michigan (U-M), Susanna Loeb of Stanford University, and James Wyckoff of the University of Virginia studied eight years of data, beginning with the 2001-2002 school year, that included 850,000 observations of grade four and five students at New York City public schools. They published their findings in a recent issue of the American Educational Research Journal.

When the researchers compared test scores for students within the same grade and school over different years, their math scores were 8.2 to 10.2 percent of standard deviation lower and their English language arts scores were 4.9 to 6.0 percent of a standard deviation lower in years where there was 100 percent teacher turnover when compared to no teacher turnover.

This is the first time researchers have compared the effects of teacher turnover on student achievement across years within the same grade and school (or across grade levels within the same school and year), rather than at turnover in an entire school or district, according to a news release from U-M.

When measuring student achievement results across grade levels within the same year and school to rule out the effects of other factors, such as a new school principal, student test scores were 7.4 percent to 9.6 percent of a standard deviation lower in math and 6.0 percent to 8.3 percent of a standard deviation lower in English language arts; and

Students of teachers who remained in the same grade and school from one year to the next were harmed by turnover.

"The average effect is negative, and it's a meaningful one," said Ronfeldt in a prepared statement. "Even though we were using different modeling strategies, we got similar results, which made us feel more confident we had gotten a true effect."

Previous research had shown mixed effects of teacher turnover, with some showing negative effects owing to loss of institutional knowledge and use of school resources on the hiring process, while others showed positive effects such as new ideas and perspectives. Some research also showed that turnover rates were higher for less effective teachers, meaning that teacher turnover could benefit overall teacher quality, but those studies didn't consider the negative effect of turnover on those who remained in their schools.

30 percent of new teachers leave the profession within the first five years, with a 50 percent higher turnover rate in high-poverty schools.